Install the materials folder from your choice to
C:\Program Files\Steam\steamapps\Your Name\team fortress 2\tf\

All include the Lambda logo

The Ellis' Cap comes with a regular logo and a blue Lambda similar to Half-Life: Blue Shift

The Superfan (Bullseye's green cap for Scout) has the option of the default Orange Lambda or a green Lambda similar to the cover of Half-Life: Opposing Force